Understanding the SDM Templates

You can use SDM templates to configure system resources in the switch to optimize support for specific features, depending on how the switch is used in the network. You can select a template to provide maximum system usage for some functions or to use the default template to balance resources.

The templates prioritize system resources to optimize support for these types of features:

•Routing—The routing template maximizes system resources for unicast routing, typically required for a router or aggregator in the center of a network.

•VLANs—The VLAN template disables routing and supports the maximum number of unicast MAC addresses. It would typically be selected for a Layer 2 switch.

•Default—The default template gives balance to all functions.

Table 7-1 lists the approximate numbers of each resource supported in each of the three templates for a desktop switch.

Table 7-1 Approximate Number of Feature Resources Allowed by Each Template

Resource

Default

Routing

VLAN

Unicast MAC addresses

6 K

3 K

12 K

IGMP groups and multicast routes

1 K

1 K

1 K

Unicast routes

8 K

11 K

0

•Directly connected hosts

6 K

3 K

0

•Indirect routes

2 K

8 K

0

Policy-based routing ACEs

0

512

0

QoS classification ACEs

512

512

512

Security ACEs

1 K

1 K

1 K

Layer 2 VLANs

1 K

1 K

1 K

The first eight rows in the tables (unicast MAC addresses through security ACEs) represent approximate hardware boundaries set when a template is selected. If a section of a hardware resource is full, all processing overflow is sent to the CPU, seriously impacting switch performance. The last row is a guideline used to calculate hardware resource consumption related to the number of Layer 2 VLANs on the switch.

Configuring the Switch SDM Template

This section describes how to configure the SDM template to be used on the switch. This section contains this configuration information:

Default SDM Template

The default template is the default desktop template.

SDM Template Configuration Guidelines

You must reload the switch for the configuration to take effect.

Use the sdm prefer vlan global configuration command only on switches intended for Layer 2 switching with no routing. When you use the VLAN template, no system resources are reserved for routing entries, and any routing is done through software. This overloads the CPU and severely degrades routing performance.

Do not use the routing template if you do not have routing enabled on your switch. The sdm prefer routing global configuration command prevents other features from using the memory allocated to unicast routing in the routing template.

Setting the SDM Template

Beginning in privileged EXEC mode, follow these steps to use the SDM template to maximize feature usage:

Command

Purpose

Step 1

configure terminal

Enter global configuration mode.

Step 2

sdm prefer {default | routing | vlan}

Specify the SDM template to be used on the switch:

The keywords have these meanings:

•default—Gives balance to all functions.

•routing—Maximizes routing on the switch.

•vlan—Maximizes VLAN configuration on the switch with no routing supported in hardware.

Use the no sdm prefer command to set the switch to the default desktop template.

The default template balances the use of system resources.

Step 3

end

Return to privileged EXEC mode.

Step 4

reload

Reload the operating system.

After the system reboots, you can use the show sdm prefer privileged EXEC command to verify the new template configuration. If you enter the show sdm prefer command before you enter the reload privileged EXEC command, the show sdm prefer command shows the template currently in use and the template that will become active after a reload.

This is an example of an output display when you have changed the template and have not reloaded the switch:

Switch# show sdm prefer

The current template is "desktop routing" template.

The selected template optimizes the resources in

the switch to support this level of features for

8 routed interfaces and 1024 VLANs.

number of unicast mac addresses: 3K

number of igmp groups + multicast routes: 1K

number of unicast routes: 11K

number of directly connected hosts: 3K

number of indirect routes: 8K

number of qos aces: 512

number of security aces: 1K

On next reload, template will be "desktop vlan" template.

To return to the default template, use the nosdm prefer global configuration command.

This example shows how to configure a switch with the routing template.

Switch(config)# sdm prefer routing

Switch(config)# end

Switch# reload

Proceed with reload? [confirm]

Displaying the SDM Templates

Use the show sdm prefer privileged EXEC command with no parameters to display the active template.

Use the show sdm prefer [default | routing | vlan] privileged EXEC command to display the resource numbers supported by the specified template.

This is an example of output from the show sdm prefer command, displaying the template in use.

Switch# show sdm prefer

The current template is "desktop default" template.

The selected template optimizes the resources in

the switch to support this level of features for

8 routed interfaces and 1024 VLANs.

number of unicast mac addresses: 6K

number of igmp groups + multicast routes: 1K

number of unicast routes: 8K

number of directly connected hosts: 6K

number of indirect routes: 2K

number of policy based routing aces: 0

number of qos aces: 512

number of security aces: 1K

This is an example of output from the show sdm prefer routing command entered on a switch: